This paper explores the role of language in the differing Rwandese and Kenyan postcolonial ethno-political realities. The national and official Kinyarwanda language did not unify the essentially monolingual Rwanda. Kiswahili could have assumed a role as common denominator, and has a new role to play in the emerging Rwandese and Kenyan ethno-political social categorisation, especially given the emergence of a new generation of native Kiswahili speakers in an era of globalization.